ENHANCED PREFERENCE FOR A PROTEIN-CONTAINING DIET IN RESPONSE TO DIETARY-PROTEIN RESTRICTION

Rats were maintained for 10 days on either a protein-free or a nutriti onally complete maintenance diet, and they were also given access to p rotein-rich and carbohydrate-rich test diets during separate daily 2-h test sessions. In Experiment 1, rats maintained on the protein-free d iet gradually and selectively increased their intake of the protein te st diet, and eventually derived 16% of their daily energy intake from the protein test diet. Rats maintained on a nutritionally complete die t ate similar amounts of the two test diets even when their total calo ric intake was matched to that of rats maintained on the protein-free diet. Ln Experiment 2, rats that developed a preference for the protei n test diet while maintained on a protein-free diet were given Purina Chow for 25 days to allow them to recover from their protein deficienc y. When these rats were later returned to the protein-free diet for 10 days, their preference for the protein test diet was immediate and su stained. However, if they were maintained on the nutritionally complet e diet after the 25-day recovery period, they initially preferred the protein test diet, but this preference diminished over days. Results o f these studies are consistent with other findings showing that rats c an learn to compensate for macronutrient deficiencies by using oral-se nsory cues. In particular, the rats' diet selection was consistent wit h their having learned a preference for the cues paired with dietary p rotein. (C) 1998 Academic Press Limited.